Methane as an effective hydrogen source for single-layer graphene synthesis on Cu foil by plasma enhanced chemical vapor deposition

A single-layer graphene is synthesized on Cu foil in the absence of H₂ flow by plasma enhanced chemical vapor deposition (PECVD). In lieu of an explicit H₂ flow, hydrogen species are produced during the methane decomposition process into their active species (CHx<4), assisted with the plasma. Notably, the early stage of growth depends strongly on the plasma power. The resulting grain size (the nucleation density) has a maximum (minimum) at 50 W and saturates when the plasma power is higher than 120 W because hydrogen partial pressures are effectively tuned by a simple control of the plasma power. Raman spectroscopy and transport measurements show that decomposed methane alone can provide a sufficient amount of hydrogen species for high-quality graphene synthesis by PECVD.A single-layer graphene is synthesized on Cu foil in the absence of H₂ flow by plasma enhanced chemical vapor deposition (PECVD). In lieu of an explicit H₂ flow, hydrogen species are produced during the methane decomposition process into their active species (CHx<4), assisted with the plasma. Notably, the early stage of growth depends strongly on the plasma power. The resulting grain size (the nucleation density) has a maximum (minimum) at 50 W and saturates when the plasma power is higher than 120 W because hydrogen partial pressures are effectively tuned by a simple control of the plasma power. Raman spectroscopy and transport measurements show that decomposed methane alone can provide a sufficient amount of hydrogen species for high-quality graphene synthesis by PECVD.

Electronic supplementary information (ESI) available: Schematic diagram of the ICP-CVD system, substrate heating by plasma, differential-pumping technique for mass spectra measurement, and transport properties of a single-domain graphene device. See DOI. 10.1039/c2nr33034b